Field of the Invention
The present invention relates to a multi-way valve and to a refrigerating machine having a circuit in which the multi-way valve is inserted.
Such multi-way valves or refrigerating machines are used, for example, in refrigerators that have a plurality of cooling compartments capable of being regulated in each case by a specific evaporator to temperatures that can be set independently of one another; they serve, there, for apportioning the refrigerant stream to one or more evaporators. The multi-way valves used at the present time in refrigerating machines are, generally, solenoid valves. These valves have a housing with a plurality of valve seats and with a closing member movable between stable positions, in each case on one of the valve seats, by magnetic force.
A solenoid valve, not actuated magnetically, having a housing with a plurality of inlets and outlets and a chamber with a plurality of valve seats associated, in each case, with an inlet or outlet is disclosed in German Published, Non-Prosecuted Patent Application DE 198 22 735 A1. The housing of this known multi-way valve includes three chambers: a middle chamber, in which a closing member is movable between two seats on opposite side walls; and two lateral chambers, into which the orifices of the valve seats issue and in each of which a spring of a form memory alloy is accommodated. The two springs press onto the closing member in the middle chamber in each case through a piston and a rod extending through the orifice of the respective valve seat. By heating a first of the two lateral chambers, the spring located therein is lengthened and presses the closing member against the valve seat leading to the second lateral chamber, the spring, at the same time, compressing the spring in the second lateral chamber.
To displace the closing body from one seat to the other, a spring not only has to apply the force necessary for deforming the other spring in each case, but, furthermore, a force that corresponds to the product of the pressure difference between the central and the lateral chamber and the cross-sectional area of the valve seat orifice. There is, therefore, the risk that, if the pressure difference is too high, the multi-way valve does not change over reliably.